internal table final

7/31/2019 Internal Table Final

1/31

2009 DCDM. All Rights Reserved. Proprietary Information. Not to be disclosed without prior written agreement.

Introduction to Internal Tables- Kunal Behary


2/31

2 2010 DCDM. All Rights Reserved. Proprietary Information. Not to be disclosed without prior written agreement.

Objectives

Introduce the structure of an Internal Table

Explore ways of defining an Internal Table in ABAP

Explore ways of filling an Internal Table in ABAP

Examine how to sort an Internal Table

Examine how to retrieve lines from an Internal Table


3/31


What is an internal table ? Internal tables provide a replica of tables or structure we working on

and then modifying, changing or creating values in the database tablein SAP.


4/31


Obsolete Version Of Internal Table i.e. with headerline

Example:

DATA :

BEGIN OF itab1 OCCURS 10,

f1,

f2,

f3,

END OF itab1.

DATA itab2 LIKE ztxlfa1 OCCURS 100.

DATA itab3 LIKE ztxlfa1 OCCURS 100 with header line.

BEGIN OF creates header LIKE does not create a header line LIKE add WITH HEADER LINE creates a header

line.


5/31


Internal Table without a Header Line

Separate Internal Table Work Area

Performance Issues

Nested Internal Tables

WHY???


6/31


Filling an internal table Example 1Tables can be filled with data by:

Reading data from a database table e.g


7/31


Filling an internal table Example 2


8/318


Filling an internal table (contd)

Inserting lines at a specified position.

Examples :

insert vendtab index 3.

The contents of the header line will be inserted before line 3.

insert lines of new_vendfrom 2 to 5into vendtab index 3.

Lines 2 to 5 of the internal table new_vend will be inserted before line 3 ofvendtab.


9/319 2010 DCDM. All Rights Reserved. Proprietary Information. Not to be disclosed without prior written agreement.

Filling an internal table (contd)

Moving complete tables

Examples :

move new_vend to vendtab.

Note :

If an internal table with a header line is involved, this header line (but not theinternal table itself) is copied by move.



Sorting an Internal Table

Data in an internal table can be sorted in a number of ways:

Examples:

data stud_tab like student occurs 10.

1)

sort stud_tab.

2)

sort stud_tab by studname, studid.

3)

sort stud_tab by stud_id descending.



Retrieving lines

Once an internal table has been filled, data can be retrieved by reading eachline of the table using a loop, or reading individual lines.

Examples :

1) loop at stud_tab.

write / stud_tab-studid.

write stud_tab-studname.endloop.

2) loop at stud_tab

where studname = Smith.

write / stud_tab-studid.endloop.



Retrieving lines (contd)

3) read table stud_tab index 5.if sy-subrc = 0.

write / stud_tab-studid.

else.

write / Record not found.

endif.

4) read table stud_tab

with key studid = 3064537.

if sy-subrc .

5) read table stud_tab

with key studname = Smithcourse = BGCC.

6) read table stud_tab with key studid

= 3165432 binary search.



Changing an internal table

The contents of a given line in an internal table can be updated using the

modifycommand. For example :

read table stud_tabwith key studid = 3354631.

if sy-subrc = 0.

stud_tab-course = BBBC.modify stud_tab index sy-tabix.endif.



Changing an internal table - Example.

TABLES: zcustomers.

DATA:

t_cust_info LIKE

STANDARD TABLE

OF zcustomers.

SELECT *

FROM zcustomersINTO TABLE cust_info.

SORT cust_info BY cnum.

READ TABLE cust_infoWITH KEY cnum = 3456755BINARY SEARCH.

IF sy-subrc = 0.

cust_info-cphone = 9654-2345.MODIFY cust_info INDEX sy-tabix.

ENDIF.

LOOP AT cust_info.WRITE: / cust_info-cnum,

cust_info-cname.ENDLOOP.



Other table commands

clear fs_area.

Clears the work area of the internal table.

refresh tablename.Removes all the line records in a table (not the header) the storage remains.

freetablename.

Deletes the internal table and releases the storage space.


16/31

Proprietary Information. DCDM Consulting.

Not be disclosed without express written consent.

Advanced Internal Tables



Objectives

Revise the structure of internal tables

Review the attributes of internal tables

Describe the three internal table kinds: standard, sorted, hashed

Examine the features and application of STANDARD internal tables

Examine the features and application of SORTED internal tables

Examine the features and application of HASHED internal tables

Distinguish between the use of work areas Vs header lines when

processing internal tables



Internal Tables as Dynamic Data Objects

f1 f2

1 A XX

2 B YY

3 C YY

Itab

data: BEGIN OF itab OCCURS 10,

f1,f2,

f3,

END OF itab.

LOOP AT itab.

write: / sy-tabix, itab-f1, itab-f2.

ENDLOOP.

WRITE: / 'done. sy-tabix =', sy-tabix,

/ ' sy-subrc =', sy-subrc.OUTPUTS:

1 A XX

2 B YY

3 C YY

sy-tabix = 99

sy-subrc = 0



Attributes of an Internal Table



Internal Table Kinds

Internal Tables can be divided into three table kinds, depending on the

possible access type required:


21/3121


Defining Internal Tables - Standard

DATA:

itab TYPE

STANDARD TABLE

OF sbookWITH NON-UNIQUE KEY bookid.

DATA: itab TYPE TABLE OF scarr.


22/3122



23/3123


Defining Internal Tables: Sorted & Hashed


24/3124


Work Area or Header Line


25/3125


Hashed Internal Table


26/3126



27/31



28/31


Internal Table Restricting Rows

Restricting rows read from an internal table.

Using FROM, TO and WHERE

- WHERE returns a subset but always performs a full table scan

LOOP AT itab WHERE f2= YY

LOOP AT itab from 2 to 3.

Use EXIT, CONTINUE or CHECK to control LOOP AT.


29/31


Internal Table single-record access


30/31


Internal Table Kinds - Summary

Standard table

Standard tables are best when you access data using an index, that is, the order ofthe data records is important but the sorting and the uniqueness are not crucial. If you

decide you need to sort the table or access it using the key or a binary search, you

can always program these functions by hand.

Sorted table

When you choose to use a sorted table, it will normally be because you want to defineand use a unique key.

When a sorted table is created the data is first sorted and then inserted.

If you have a table with few entries but lots of accesses that change the contents, asorted table may be more efficient than a standard table in terms of runtime because

of binary search access.


31/31

Internal Table KindsSummary (contd)

Hashed table

The hash algorithm calculates the address of an entry based on the key. This means

that, with larger tables, the access time is reduced significantly in comparison with a

binary search. But when you use a loop with a hashed table, the whole table has to

be scanned. Because the data records are usually totally unsorted, a sorted table

may be more useful if you have a loop over the beginning of a key. Alternatively, you

could also sort the hashed table.

Hashed table is only beneficial if you want to keep large amounts of data locally inthe program and you mostly access it only to read it. You must ensure that youdesign your hashed table so that it is possible to specify the full key when you access

it from your program.

Typical use for hashed tables is for buffering or bundling large amounts of data from

several database tables when an ABAP Dictionaryview or a nested SELECTstatement is not possible.

internal table final

Documents